Ignition arrangements for internal combustion engines

ABSTRACT

An arrangement for providing ignition pulses for an internal combustion engine while at the same time inhibiting ignition pulses from being applied when said engine is operated in the improper direction. Ignition pulses are produced through an ignition coil which has its primary winding connected to a capacitor charged through a magneto generator. Discharging of the capacitor is controlled through a thyristor which, in turn, is fired through the application of pulses derived from pulse emitters. The thyristor is switched to the conducting state, during improper operating direction of the engine, by the voltage pulse which causes charging of the capacitor when the thyristor is in the nonconducting state.

United States Patent Gemander air. 1, 1972 [54] IGNITION ARRANGEMENTSFOR 3,566,188 2/1971 Minlcs ..123/148 E X MNTIERNAL COMBUSTION ENGINES3,435,264 3/1969 Brand et a1. ..123/148 E X [72] Inventor: GeorgGemander, Nurnberg, Germany primary Examiner Laul-ence M goodridge [73]Assignee: Robert Bosch Gmblii, Stuttgart, Germany A"mey M1chael smker[22] Filed: July 15, 1970 [57] STRACT [21] Appl. No.: 55,080 Anarrangement for providing ignition pulses for an internal combustionengine while at the same time inhibiting ignition pulses from beingapplied when said engine is operated in the [30] Forelgn Apphcauon EmmyDam improper direction. Ignition pulses are produced through an July 16,1969 Germany ..P 19 36 105.8 ignition coil which has its primary windingconnected to a capacitor charged through a magneto generator.Discharging [52] U.S.Cl ..123/149 A, 123/41, 123/ 146.5 A, of thecapacitor is controlled through a thyristor which, in 123/149 C, 123/149D turn, is fired through the application of pulses derived from [51]llnt.Cl ..F02p 1/00 pulse emitters. The thyristor is switched to theconducting [58] Field of Search ..123/ 148 E, 149 A, 149 D, 41, state,during improper operating direction of the engine, by 123/ 146.5 A;315/209 the voltage pulse which causes charging of the capacitor whenthe thyristor is in the nonconducting state. [56] Reterences Cited 11thC in 8 Drill lFigurm UNITED STATES PATENTS Burson ..123/148 E X PatentedMarch 14, 1912 3,648,675

2 Sheets-Sheet l IN VE NTOR Geor g GEMANDER l-ll a [fl-l his ATTORNEYPatented March 14, 1972 2 Sheets-Sheet 2 I Fig.4c

his ATTORNEY IGNITION ARRANGEMENTS FOR INTERNAL COMBUSTION ENGINESBACKGROUND OF THE INVENTION The present invention resides in an ignitionarrangement for internal combustion engines in which a capacitor becomescharged from a magneto generator, and then becomes discharged at theinstant of ignition through the primary winding of an ignition coil,upon actuation of an electronic circuit. The secondary winding of theignition coil is connected to the spark plug of the engine.

It is known in the art to provide a thyristor in such electronicallycontrolled capacitor type of ignition arrangements, and to fire thethyristor at the instant of ignition through a voltage pulse. Thevoltage pulse for firing the thyristor is generated through a magnetictype of generator or emitter which operates in conjunction with a movingelement that passes or conducts flux lines. As soon as this elementwhich passes or conducts flux lines, moves beneath the pole pieces ofthe pulse emitters or generators, in operation of the engine, themagnetic circuit of the pulse generator becomes briefly closed. As aresult of the closure, and the change of the magnetic flux within theinduction coil of the generator, thereby, a positive voltage pulse witha subsequently following negative pulse become induced. Whereas thepositive pulse is used for ignition purposes, the negative pulses areblocked through a diode, and thereby remain ineffective. Such ignitionarrangements have, however, the disadvantage that when operating inreverse as, for example, at the start, the previous negative pulsederived from the pulse generator, becomes a positive pulse due to thechanged direction of motion. The resulting positive pulse causes thethyristor to be switched to the conducting state, and accordingly thecapacitor becomes discharged through the ignition coil and a spark isthereby applied at the spark plug. With such operation of the sparkplug, the engine is aided in running in the wrong direction.

Accordingly, it is an object of the present invention for providing, inan ignition combustion engine, means for inhibiting the generation ofsparks or sparking of the plugs within the engine, when the latteroperates in the reverse direction. It is particularly an object of thepresent invention to provide such an arrangement for engines having oneor more cylinders.

The objects of the present invention are achieved by providing forswitching the thyristor to the conducting state, as soon as the halfwave of a voltage is produced during the wrong direction of motion ofthe magneto generator. Such halfwave would, otherwise, cause charging ofthe capacitor which is connected to the magneto generator, should theelectronic switching element in the form of the thyristor be turned off.The switching of the thyristor, thereby, takes place in the simplestmanner when the engine operates in the wrong direction, and suchswitching of the thyristor is accomplished by the voltage pulse of amagnetic generator or pulse emitter which switches the thyristor to theconducting state. When the engine is operated in the proper direction,the pulse emitter provides the pulse for switching the thyristor to theconducting state at the instant of ignition.

SUMMARY OF THE INVENTION An ignition arrangement for internal combustionengines in which a capacitor charged by a magneto generator dischargesthrough the primary winding of an ignition coil upon firing of athyristor. The anode-cathode path of the thyristor is connected inseries with the primary winding of the ignition coil. The gate of thethyristor has a voltage pulse applied to it through a pulse emitter. Thethyristor is switched to the conducting state upon generation of avoltage pulse which would charge the capacitor through the magnetogenerator, at the instunt of ignition, and when the thyristor is in thenon-conducting state. When the engine is operating in the improperdirection, the thyristor is switched to the conducting state andinhibits, thereby, the charging of the capacitor.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional ob jects and advantages thereof,will be best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a functional schematicdiagram of an internal combustion engine with two cylinders and amagneto generator for charging an ignition capacitor, in accordance withthe present invention;

FIG. 2 is a circuit diagram of the arrangement of FIG. 1;

FIGS. 3a, 3b and 3c are voltage waveforms of the armature windinginduced pulses of the ignition generator arrangement when operated inthe proper direction of motion; and

FIGS. 4a, 4b and 4c are voltage waveforms prevailing in the ignitionarrangement when the engine is operated in the improper direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, andin particular to FIG. I, an internal combustion engine with twocylinders and of two cycle design, is provided with a magneto generatorltll. This generator consists of a pole wheel 131 provided with foursymmetrically arranged permanent magnets 12. These permanent magnets 12are arranged so that they are situated with alternating polarity. Thegenerator, furthermore, has an armature plate 13 upon which are mounteda charging armature M for producing the ignition energy, and ignitioncapacitor I5 for storing the ignition energy, a well as two oppositelylying magnetic pulse emitters l6 and 17. The elements mounted upon thearmature 13, are connected to a circuit 22 situated outside of thegenerator 10, through interconnecting lines 18,19,20 and 21. Twoignition coils 23 and 24, are, furthermore, connected to the ignitioncircuit 22. The high voltage portions of these ignition coils haveterminal lines 25 and 26 connected to both spark plugs 27 and 28 whichare arranged in the combustion chamber of the engine.

The functional operation of the ignition arrangement may be obtainedfrom FIGS. 2, 3 and 4. FIG. 2 shows precisely the circuit constructionof the ignition arrangement shown in FIG. 1. With normal rotation in thenormal direction, an alternating voltage U is generated within thecharging armature M of the generator 10, through the rotating pole:wheel II. This voltage U is shown in FIG. 3a. The next positive halfwavewhich appears as a result of the electrical energy produced in themagnetic generator 10, is applied to the ignition capacitor 15, througha diode 30. As a result, the ignition capacitor 15 becomes charged.Since the diode 3t] prevents discharging of the ignition capacitor 15through the charging armature 14, the capacitor voltage U appears asshown in FIG. 3c. In this latter diagram, the capacitor voltage has amaximum value for the positive voltage halfwave of substantially volts.

With further rotation, the element 29 which is connected to the motorshaft and which serves to pass the flux lines, is moved beneath themagnetic generator 16 at the instant at which the negative halfwavewithin the charging armature M has attained its maximum value. Throughthe element 29, variation in the magnetic flux takes place within thegenerator 16. As shown in FIG. 3b, first a positive and then anegatively following voltage pulse U of approximately 1.8 volts isinduced. The positive voltage pulse is applied to the control gate of athyristor 32, through a diode 31. With the application of this positivevoltage pulse to this thyristor, the latter is switched to theconducting state. The ignition capacitor 15 becomes thereby suddenlydischarged, as shown in FIG. 3c, since the circuit through the primarywinding 23a of the ignition coil 23 and the thyristor 32, is close toground. As a result, an ignition voltage is induced within the secondarywinding 23b of the ignition coil 23. This ignition voltage is thenapplied to the spark plug 27 for the purpose of producing a spark acrossthe electrodes of the plug.

With further rotation of the magnetic pole wheel 11, a I

second positive halfwave voltage is induced within the charging armatureor charging coil 14, and this voltage halfwave serves to charge againthe ignition capacitor through the diode 30. Since the two magneticgenerators l6 and 17 lie opposite to each other as shown in FIG. 1, theelement 29 is moved beneath the second generator 17 with furtherrotation of l80. As a result, a positive and subsequently followingnegative voltage pulse are also here generated. The positive voltagepulse is applied to the control gate of a second thyristor 34 through afurther diode 33, and switches the thyristor, thereby, to the conductingstate. In this manner, the ignition capacitor 15 becomes dischargedthrough the primary winding 24a of the second ignition coil 24, andthrough the thyristor 34. In this manner, a high voltage results also inthe secondary winding 24b of the ignition coil 24, and this high voltageis applied to the spark plug 28 for producing a further spark. Thenegative voltage pulse appearing at both magnetic generators 16 and 17have no effect upon the associated thyristors 32 and 34, since thediodes 31 and 33 will not conduct. To protect the thyristors 32 and 34against excess voltages, the control gates are connected to groundpotential through a resistor 35 and a capacitor 36 connected in paralleltherewith.

When the internal combustion engine is operated in the wrong rotationaldirection, the voltage halfwaves induced within the charging coil orarmature 14 have the reversed sequence and reverse direction. The lastnegative halfwave shown in FIG. 3a, becomes thereby the first positivehalfwave, as shown in broken lines in FIG. 4a, during incorrectrotational direction. This also applies to the voltage pulses of themagnetic generator 17 whose negative pulses now become positive ones, asshown in FIG. 4b. These positive pulses are applied to the control gateof the thyristor 34 and switch the latter to the conducting state at theinstant that the positive halfwave at the charging coil 14 begins. Thecircuit through the charging coil 14, diode 30, as well as through theprimary winding 24a of the ignition coil 24, becomes closed. As aresult, the charging of the ignition capacitor 15 is prevented.

Since the primary winding 24a of the ignition coil 24 has 'a relativelylow resistance value, the actual voltage at the charging armature orcharging coil 14 is very small, and consequently the voltage at theignition capacitor 15 is also small. This may be seen from the extendedline in FIGS. 4a and 4c. Through such action, therefore, no sparkappears at the spark plug 28.

Since the thyristor 34 remains in the conducting state as long ascurrent flows in the circuit, the thyristor becomes turned off firstafter the end of the positive halfwave from the charging armature orcoil 14. With further rotation of the pole wheel 11, a negative halfwavebecomes now induced within the charging armature or coil 14, and thisnegative halfwave remains ineffective for the ignition arrangement,because the diode 30 remains in the non-conducting state. First afterthe positive halfwave at the charging armature or coil 14, can theignition capacitor 15 become charged through the diode 30. Since,however, at that instant of time the element 29 becomes moved beneaththe other generator 16, and a positive and negative voltage pulsebecomes generated therein, the thyristor 32 becomes switched to theconducting state through the diode 31. As a result, the same procedureas before is repeated with respect to the thyristor 34. As shown in FIG.4c, an insignificant voltage U appears at the capacitor 15 during thepositive halfwave in the charging armature 14 upon resetting, butcharging of the capacitor does not take place.

The cooperative arrangement of the generator 16 and 17 with the element29 is essential for assurance of proper resetting of the ignitionarrangement. It is necessary to arrange the element 29 so that its rearend produces a positive pulse for the thyristors 32 and 34 at theinstant of time when it is moved beneath the magnetic generator 16 and17, when the engine is rotated in the wrong direction. Through suchconditions, a positive halfwave begins within the charging armature orcoil 14, and charging of the ignition capacitor 15 is thereby avoidedwith safety.

The element 29, in an embodiment, extends preferably over an arc of 0.21radians, or approximately 12. Accordingly, when the engine is rotated inthe proper direction, the pulse produced with its front end within thegenerator 16 or 17, appears within the region of the maximum value ofthe negative halfwave of the charging armature 14. This pulse determinesthe ignition instant and is used as the control pulse for thethyristors. Due to the narrow element 29, the magnetic circuit of thegenerator is directly closed and opened again in sequence. It has beenfound, thereby, that the positive and the negative generator pulse whichfollows directly, is larger than what would occur for a longer element29, in which case the two generated pulses do not follow each otherdirectly. The arrangement, therefore, also operates safely with smallbackup speeds.

The present invention is not limited for these particular embodimentsillustrated. The present invention is, instead, applicable to singlecylinder as well as multicylinder engines. in the latter case, theignition arrangement is provided with a plurality of poles in themagneto generator, and a magnetic generator, furthermore, is providedfor each thyristor control and cooperates with the rotating element 29,for example.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied inignition arrangements for internal combustion engines, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. An ignition arrangement for internal combustion engines comprising,in combination, ignition coil means with primary and secondary windingsfor producing an ignition pulse in said secondary winding; chargingcapacitor means connected to said primary winding means for storing theignition energy; connection means between said charging capacitor meansand said primary winding means for discharging said ignition energythrough said primary winding means; magneto generator means connected tosaid capacitor means for charging said capacitor means, said capacitormeans discharging through said connection means and through said primarywinding for producing said ignition pulse in said secondary winding;electronic switching means connected in series with said primarywinding; means for connecting the series combination of said switchingmeans and said primary winding in parallel with said capacitor means,said switching means and said primary winding being a conductive pathacross said capacitor means when said switching means is in theconducting state; pulse emitting means coupled to said engine andemitting pulses at spaced intervals; means for connecting said pulseemitting means to said switching means for controlling the state of saidswitching means, said switching means being switched to the conductingstate by said pulse emitting means during a first operating direction ofsaid engine whereby said capacitor means is inhibited from being chargedby said generator means so that said ignition pulse is not produced insaid secondary winding,

said switching means being switched to the non-conducting state whensaid engine is operating in a second direction whereby said capacitormeans is charged by said generator means to produce said ignition pulseonly when said engine is operating in said second direction.

2. The ignition arrangement as defined in claim ll, wherein saidelectronic switching means comprises thyristor means.

3. The ignition arrangement as defined in claim 1 including spark plugmeans connected to said secondary winding of said ignition coil means.

4. The ignition arrangement as defined in claim 2, wherein said pulsesfrom said pulse emitting means switch said thyristor means to theconducting state at the instant of ignition when said engine operates inthe second direction.

5. The ignition arrangement as defined in claim 4, wherein said pulseemitting means comprises electromagnetic means.

6. The ignition arrangement as defined in claim 1 including diode meansconnected to said capacitor means for charging said capacitor means withpositive voltage from said magneto generator means, said electronicswitching means being a thyristor switched to the conducting statethrough positive voltage pulses from said pulse emitting means.

7. The ignition arrangement as defined in claim 1, wherein said pulseemitting means comprises induction coil means; ferromagnetic meansmovable in proximity of said induction coil means so that a voltage isinduced within said induction coil means for switching said electronicswitching means to conducting state within substantially the maximumnegative region of the voltage from said magneto generator means duringsaid operating direction of said engine.

8. The ignition arrangement as defined in claim 7, wherein saidferromagnetic means comprises a substantially elongated ferromagneticelement extending over an arc of 0.21 radians.

9. The ignition arrangement as defined in claim 1, wherein said enginehas a plurality of cylinders, each of said cylinders being associatedwith one electronic switching means and one pulse emitting means, all ofsaid pulse emitting means being operated with one ferromagnetic elementmovable relative to said pulse emitting means.

10. The ignition arrangement as defined in claim 9, wherein saidelectronic switching means comprises a thyristor.

1. An ignition arrangement for internal combustion engines comprising,in combination, ignition coil means with primary and secondary windingsfor producing an ignition pulse in said secondary winding; chargingcapacitor means connected to said primary winding means for storing theignition energy; connection means between said charging capacitor meansand said primary winding means for discharging said ignition energythrough said primary winding means; magneto generator means connected tosaid capacitor means for charging said capacitor means, said capacitormeans discharging through said connection means and through said primarywinding for producing said ignition pulse in said secondary winding;electronic switching means connected in series with said primarywinding; means for connecting the series combination of said switchingmeans and said primary winding in parallel with said capacitor means,said switching means and said primary winding being a conductive pathacross said capacitor means when said switching means is in theconducting state; pulse emitting means coupled to said engine andemitting pulses at spaced intervals; means for connecting said pulseemitting means to said switching means for controlling the state of saidswitching means, said switching means being switched to the conductingstate by said pulse emitting means during a first operating direction ofsaid engine whereby said capacitor means is inhibited from being chargedby said generator means so that said ignition pulse is not produced insaid secondary winding, said switching means being switched to thenon-conducting state when said engine is operating in a second directionwhereby said capacitor means is charged by said generator means toproduce said ignition pulse only when said engine is operating in saidsecond direction.
 2. The ignition arrangement as defined in claim 1,wherein said electronic switching means comprises thyristor means. 3.The ignition arrangement as defined in claim 1 including spark plugmeans connected to said secondary winding of said ignition coil means.4. The ignition arrangement as defined in claim 2, wherein said pulsesfrom said pulse emitting means switch said thyristor means to theconducting state at the instant of ignition when said engine operates inthe second direction.
 5. The ignition arrangement as defined in claim 4,wherein said pulse emitting means comprises electromagnetic means. 6.The ignition arrangement as defined in claim 1 including diode meansconnected to said capacitor means for charging said capacitor means withpositive voltage from said magneto generator means, said electronicswitching means being a thyristor switched to the conducting statethrough positive voltage pulses from said pulse emitting means.
 7. Theignition arrangement as defined in claim 1, wherein said pulse emittingmeans comprises induction coil means; ferromagnetic means movable inproximity of said induction coil means so that a voltage is inducedwithin said induction coil means for switching said electronic switchingmeans to conducting state within substantially the maximum negativeregion of the voltage from said magneto generator means during saidoperating direction of said engine.
 8. The ignition arrangement asdefined in claim 7, wherein said ferromagnetic means comprises asubstantially elongated ferromagnetic element extending over an arc of0.21 radians.
 9. The ignition arrangement as defined in claim 1, whereinsaid engine has a plurality of cylinders, each of said cylinders beingassociated with one electronic switching means and one pulse emittingmeans, all of said pulse emitting means being operated with oneferromagnetic element movable relative to said pulse emitting means. 10.The ignition arrangement as defined in claim 9, wherein said electronicswitching means comprises a thyristor.